Inspection window arrangements



Nov. 3, 1964 P. WEKER INSPECTION WINDOW ARRANGEMENTS 2 sheets-snakt y1 Filed Sept. 20; 1961 INVENroR zw uw,

ATTORNEY S Nov. 3, 1964 A Filed Sept. 20, 1961 P. WEKER INSPECTION WINDOW ARRANGEMENTS 2 Sheets-Sheet 2 NveNToR BY zldwwa;

A'rToQNEYs United States Patent O 3,154,821 INSPECTIN WINDUW ARRANGEMENTS Peter Welker, Bicknacre, England, assigner to The Marconi Company Limited, london, England, a British company Filed Sept. Ztl, 1961, Ser. No. 139,52lL Claims priority, application Great Britain, Oct. 13, 1960, 35,170/60 3 Claims. (Cl. Ztl- 405) This invention relates to inspection window arrangements and has for its object to provide improved inspection window arrangements for enabling the operation of furnaces and other devices likely to deposit obscuring matter on an ordinary viewing window to be satisfactorily viewed, i.e. seen by eye r by a television camera. The invention is of wide application, and among the many purposes to which it may be applied are ame viewing in power house boiler furnaces, viewing of combustion in open hearth furnaces, slab reheat furnaces and blast furnaces; viewing of combustion or flames in rocket engines; and viewing of so-called soaking pits as used in the iron and steel industry.

There are numerous cases, such as those just mentioned, where it is very desirable to observe the operation of a furnace or other device either directly or by means of a television camera through a window in the device, but where it is difficult or impossible to do so through an ordinary glass window because of fouling or obscuring of the inside of the window by deposited dirt or discoloration. in the case, for example, of a blast furnace or a power house boiler furnace an ordinary glass inspection window is often impractical because of the high temperatures involved and even if special temperature-resistant, so-called toughened or armour glass is employed for the window it is apt to be soon so obscured or discoloured on the inside by the action of the flames and hot gases that it becomes diflicult or impossible to see through even by eye, let alone a teievision camera. The blowing of an air blast on the inside of such an inspection window, as has been proposed, does not provide a satisfactory solution of the problem even in those cases-by no means all-where such an air blast is, for other reasons, permissible or con# venient.

The present invention seeks to overcome these diiiiculties in a practical, satisfactory and convenient manner.

According to this invention, an inspection window arrangement comprises a cooled substantially transparent window or structural sheet over a port in a wall of the device whose interior area is to be inspected and means for covering the inside surface of said window with a thin, substantially uniform, continuously flowing sheet of substantially transparent liquid.

Although it is possible to use other liquids chosen with due regard to the nature of the interior of the device to be inspected, the preferred liquid is water and in the great majority of cases water will be used.

Again, although it is possible to use other materials for the window, glass-toughened or armour glass in the case where the device to be inspected is a high temperature furnace-is the preferred transparent material used to cover the port.

By suitably choosing the rate of flow of the liquid over the inside surface of the window, and ensuring that the ice draw-off or escape path for liquid which has passed over the inside surface of the window is such that the escaping liquid is not sufficiently obstructed to produce a material amount of back pressure, the surprising result can be secured that a permanent though continuously moving substantially uniform sheet of liquid remains in contact with the inside window surface-by surface-tension effectand that a human observer or television camera viewing through the Window can see through a permanently substantially transparent window and substantially transparent inner covering of liquid thereon with little or no obstruction to the view in conditions in which a plain simple window would soon be obscured.

In a preferred embodiment of the invention for a furnace, a double window consisting of two spaced sheets of substantially transparent material-preferably glass-is employed and fiuid, again preferably water, is also pumped continuously through the inter-sheet space, filling it and serving for cooling purposes, the liquid covering being, as before, on the inner face of the inner sheet, i.e. on the window face nearest the interior of the furnace. In such an embodiment, although the inner sheet is, as before, preferably of toughened or armour glass, the outer sheet may, in the interests of economy, be ordinary glass.

The liquid covering is preferably produced by means including a liquid flow member having a liquid inlet, a jet guide plate extending along one edge of the window area surface over which the liquid is to iiow and spaced a short distance from said surface so as to leave a narrow gap for liquid to emerge and iiow over said surface, and a drain arrangement to collect and freely lead ofi` liquid which has passed over said surface in Contact therewith.

Preferably also the window, with the means for producing the liquid covering on the inner surface thereof, is attached to the device to be inspected with the interposition of means including a liquid cooled metailic spacer member on the inner side of said means for producing the liquid covering.

In the preferred embodiments of the invention the liquid covered window surface is verticai or approximately so, but experiment has shown that the invention will operate satisfactorily with the liquid covered window surface at a considerable angle to the vertical-indeed, approaching the horizontal. The important requirement to be satisfied, in order to obtain the benefits of the invention, is that an unbroken substantially uniform covering or" liquid in Contact with the inside surface of the window shail be maintained. The maintenance of such a covering depends on a number of factors, the main ones being the rate of flow of the iiquid and its surface tension, the operating pressure and temperature inside the furnace or other device to be inspected, and the maintenance of suiicient freedom of escape of the liquid which has owed over the surface to ensure that back pressure wiil not cause the liquid covering to break up or lose adherence with the window surface. if the operating pressure in the furnacel or other device is high enough it may be possible, in some cases, for the liquid covered window surface to be horizontal but, in the great majority of cases, it will be more or less vertical with liquid iniet at the upper edge of the window area and liquid outlet at the lower edge. The rate of liquid flow for best results is rather criticalY and is best found by trial and error in each individual case. In order to secure better constancy of rate of liquid ow it is preferred notV to pump liquid direct to the window area but to pump the liquid to a header tank with a iioat controlled inlet or like device giving substantially constant head and take the liquid from the tank to said area so that the rate of liquid ow is determined by a substantially constant Ypredetermined hydraulic head.

Where a double windo-w is employed with a liquid cooled/space between the two window sheets constituting the window and/ or Where a liquid cooled metallic spacer member is employed, the same liquid (normally water) may be employed for said space and/or said spacer member as is employed for the liquid covering, the said liquid being fed to the window to constitute the liquid covering after passing through said space and/or spacer member. With this arrangement the liquid of the liquid covering will be warmed before being used as such.

The invention is illustrated in the accompanying'draw- -ings in which FIGURE 1 is a schematic sectional view of one embodiment of the invention as applied to a furnace, and FIGURE 2 is an elevational View showing the liquid iiow member incorporated in the arrangement of FIGURE l, but with a furnace wall, spacer member and outer ring member (shown in FIGURE l) omitted from FIGURE 2.

Referring Vto the drawings, 1 represents, broken away, part of a vertical wall of .a furnace havingpa circular port, the circular wall of which is referenced VZ. Attached to the outside of the furnace wall by any convenient means, not shown, is a heat insulating spacer 3 also sho-wn broken away and made, for example, of asbestos brick -or other suitable refractory material. The spacer 3 has a conically tapered aperti re, the wail of which is referenced 4. Attached to the 'outer face of the spacer 3, by means also not shown, is a brass cooling spacer member 5 of annular form with a central hole, the circular wall of which is referenced 6. AS will be seen, the walls 6, 4 and 2 continue into one another. The member 5 has an annular cooling space '7 into and from, which cooling water is fed by means of inlet and outlet pipes (not shown) so that the space '7 is continuously full of water. Outward-ly of the member 5 is a liquid rlow member LFM also made of brass. This ilow member has an inlet pipe S (see FIGURE 2) to which water at substantially constant predetermined hydraulic head is fed from a float or similarly controlled header tank (not shown) into which water is pumped, the float control being of any convenient form well known per se to maintain a substantially constant head of water in the tank.V The pipe S continues into a. flat roughly ribbon sectioned pipe 9 through a tapered are 1d, the included taper yangle of which may conveniently be aboutY 123.

The arrangement of the pipes 8, 1t) and 9 is for theY object of obtaining a .steady smooth flow of water'in the ance to ow as possible and thence to a drain, not shown, whence it returns to the header tank.

The glass sheet 14 is the inner sheet of a double window comprising two parallel spaced glass sheets 14 and 17 of which the latter may be ordinary glass. The flow space 13 between lthe sheets 14 and 17 is lled with water which is pumped through -it continuously by means of inlet and outlet pipes IP and OP respectively.

Y A compressible ring gasket 19 made of suitable synthetic material, for example, that known under the registered trademark Bakelite, is interposed between sheets 1liand 1'7 to provide the required sealed space between the sheets. Outwardly of the dual plate structure 14, 17 and gasket 19 is a clamping structure including compressible rubber or simi-lar material packing rings 2t), clamping rings 22, made for example of asbestos bre, and an outer ring structure 23 of the same or similar material. This .sealing and clamping structure is held assembled to the spacer member 5 by clamping screws 21 screwed into the member 5.

The water in the space 7 of the member 5 and in the space 1S between the glass sheets 1d and 17 is merely cooling water, the liquid covering over the inner surface of the window being provided in accordance with this invention by the watery which ows through the space 13. This water covering over the inner surface of the window is not shown in the drawings, but it is quite thin, being of a thickness of the same order as the spacing between the member 12 and the adjacent face of the glass sheet 14. In a practicalcase, this spacing might be about .026. It -is possible to mate land arrange the liquid i flow Vmember LPM so that this spacing may be adjusted flattened pipe 9 with a minimum of turbulence or other v disturbancej Water flows Vdown the pipe 9 Vas indicated by the arrows-11 and is guided by means of a jet guide plate or member 12. to pass through a narrow strip-like space 13 left between the flat vertical face of lthe member 12 and the inner iat surface of a toughened glass window sheet 14. A flat substantially uniform thin sheet of water accordingly flows downwards over the inner face of the glass windowsheet 14 adhering tov it by surface tension aided by any pressure there may be inside the furnace.k The window area proper, i.e. the area through which the interior of the furnace may be observed, is the approximately, D-shaped area, the edge of which isrrefj erenced 15 in FIGURE 2, the horizontal edge, to which the upper of the two referencesY 15in FIGURE 2-is applied, being the edge at which the water emerges through f the space 13. After owingacrosstthe Windowarea in contact with the inner face of the glass sheet 1li the water passes freely into an :outlet pipe 16 odering as little resist-V when in use. Preferably, however, the best spacing forV any particular application is determined Yby' trial and error and the structure dimensioned to suit the results ofV experiment. i

As already explained, the rate of liquid flow over the inner surfa of the window is rather critical for best results and it may be convenient in somecases to make the rate of iiow adjustable, for example, by Vproviding means for adjusting `the hydraulic head determining that rate of flow. In a practical example which has been Y experimentally tested lfor the viewing of the inside of a cases, the water passing from the header tank through t.

the cooling spaces Tand 18 and then to the inlet pipe S.

It is, ot course, necessary to preserve a high degree of cleanliness in the water and any known filtering ortdirtseparating means (not shown) may beprovided for this purpose; Also the Hatter and more closely parallel the surfaces-of the sheets 14 and 17 are the lessdistortion of view there will be.V Y1

The member 23 will in practice be provided with suitable attachment means (not shown) forattaching a television camera for viewing the inside of the furnace through the glass sheets 17 and 1.4 andthe fion/ingk liquid sheet in contact .with and on the inside of the'. sheet 14.

I claim: Y 'j t 1. In a furnace or like structure theinterior of which is .to be inspectedrfrorn the exterior thereof, a wall por.`

tion having aport; two substzm'tiallyY transparent sheets;

means mounting ,said4 sheets on said wall portion in spaced relation Vto one another to close said Vport` and .to provide a window Vthereforthe spacing of said sheets providing a flow space between said sheets; means for di-` recting cooling huid to ow through said dow space; and v means for covering the inner surfaceV of theA one of said transparent sheets which is innermost with respect to said Wall portion with a thin substantially uniform lm of substantially transparent liquid.

2. A construction according to claim 1 wherein said means for covering said inner Asurface, of said innermost sheet with a thin, substantially uniform, lm of substantially transparent liquid comprises a liquid ow member having a liquid inlet; a jet guide plate extending along one edge of said substantially transparent sheet and spaced a short distance from said inner surface thereof and leaving a narrow gap for How of liquid from said guide plate onto and over said inner surface; and a drain -for co1- lecting and freely leading oit liquid which has passed o-ver said surface.

3. A construction according yto claim 1 wherein said means for mounting said sheets on said wall portion includes a metallic cooling member interposed between said innermost sheet inner surface and said wall portion.

References Cited in the le of this patent UNITED STATES PATENTS 1,101,172 Frassier June 23, 1914 1,402,416 Hagberg et al. Jan. 3, 1922 1,843,828 McNaught Feb. 2, 1932 2,357,753 Mutuszak Sept. 5, 1944 2,377,863 Campbell Iu-ne 12, 1945 2,850,005 Good et al. Sept. 2, 1958 FOREIGN PATENTS 4,367 Great Britain Nov. 21, 1877 11,670 Netherlands Sept. 15, 1924 

1. IN A FURNACE OR LIKE STRUCTURE THE INTERIOR OF WHICH IS TO BE INSPECTED FROM THE EXTERIOR THEREOF, A WALL PORTION HAVING A PORT; TWO SUBSTANTIALLY TRANSPARENT SHEETS; MEANS MOUNTING SAID SHEETS ON SAID PORT AND TO PRORELATION TO ONE ANOTHER TO CLOSE SAID PORT AND TO PROVIDE A WINDOW THEREFOR, THE SPACING OF SAID SHEETS PROVIDING A FLOW SPACE BETWEEN SAID SHEETS; MEANS FOR DIRECTING COOLING FLUID TO FLOW THROUGH SAID FLOW SPACE; AND MEANS FOR COVERING THE INNER SURFACE OF THE ONE OF SAID TRANSPARENT SHEETS WHICH IS INNERMOST WITH RESPECT TO SAID WALL PORTION WITH A THIN SUBSTANTIALLY UNIFORM FILM OF SUBSTANTIALLY TRANSPARENT LIQUID 